Means for incorporating materials having magnetic and/or electric properties in electron interaction devices



0d. 20, 1970 J, M, OSEPCHUK ETAL 3,535,579

l MEANS FOR INCORPORATING MATERIALS .HAVING MANETIG AND/OR ELECTRIC PROPERTIES IN ELECTRON INTERACTION DEVICES Filed D80. 19, 1968 United States Patent O M 3,535,579 MEANS FOR INCORPORATING MATERIALS HAV- ING MAGNETIC AND/OR ELECTRIC PROPER- TIES IN ELECTRON INTERACTION DEVICES John M. Osepchuk, Concord, Mass., and William H. Wright, Jr., Neptune, NJ., assignors, by direct and mesne assignments, to the United States of America as represented by the Secretary of the Army Filed Dec. 19, 1968, Ser. No. 785,179 Int. Cl. H01j 25/34 U.S. Cl. S- 3.5 12 Claims ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

BACKGROUND OF THE INVENTION Electron interaction and crossed field microwave devices have in many instances been combined with the class of components generically referred to as isolators, circulators, gyrators ad phase Shifters of ferric materials. Such separate devices require consideration of additional losses in the system as well as additional expense. Many crossed field devices such as for example magnetrons, Amplitrons, platinotrons and stabilitrons have in the past been improved in performance by the regulation of the output frequency signals. Certain characteristics referred to in the art as frequency pulling and frequency pushing require the utilization of ferrite materials in some part of the system which involves consideration of the external matching load impedances.

Phase Shifters also are now well known in the art and represent a class of devices often found in microwave systems in conjunction with oscillators and amplifiers to provide certain preferred characteristics in the propagation of energy. Again the provision of separate functional devices requires additional load effect considerations.

Still another class of devices also of the cross field generic class include backward and forward wave oscillators or amplifiers of the M type utilizing the electron interaction phenomenon. Similarly, high powered multicaviticd klystrons, along with traveling wave devices and O type tubes all rely heavily on certain desired characteristics for the exchange of energy between a traveling electron beam and electromagnetic wave components. Spurious oscillations as well as instabilities in the output signals may result from undesirable forward wave and backward wave components which require compensation at an external point in the microwave system to remove or suppress such components.

In the prior art the use of certain microwave materials have been impeded by reason of the failure of the tube technology and processing techniques to permit the incorporation of such materials within the devices having the evacuated atmosphere. Exemplary of such materials Patented Oct. 20, 1970 ICC are a class of devices referred to as ferroelectric which are of a dielectric composition and possess piezoelectric properties as well as certain electrical properties analogous to magnetic properties. Barium titanate as well as barium niobate are exemplary of such materials. A group of porous ferrite materials have also been excluded from incorporation in microwave devices with the result that only the denser garnet type of materials could be employed.

Primarily in evacuated electron interaction devices various glass fritting techniques have been employed to secure ferrite materials to a metallic wall defining the envelope or electrode structure. Such bonding techniques can effect the ferrite material properties in view of the high temperature required in the process. Further, the incorporation of such materials has been found to be incompatible with the remaining tube processing Operations including brazing, welding, heliarc welding, as well as soldering, which inhibit the utilization of temperature senstive materials. A need therefore exists to provide for the incorporation of the so-called exotic materials within evacuated electron interaction devices. An accompanying saving in cost may be realized in that the existing magnetic field producing means may also be utilized thereby eliminating the need for separate external magnets. Additionally, the improvement in tube operating parameters is always paramount to provide greater overall efficiencies.

The present invention therefore suggests and discloses a means for overcoming the prior art processing problems and permits a greater utilization of exotic materials in evacuated electron interaction devices.

SUMMARY OF THE INVENTION In accordance with the teachings of the invention an encapsulating structure is provided for mechanically mounting a body of an exotic material within a vacuum enclosure of an electron interaction device without exposure of the material to the vacuum atmosphere. For the purposes of the present invention the term exotic materials is defined as including the group of uncommon materials such as ferrites, ferrimagnetic or ferromagnetic materials, semiconductors, as well as those materials displaying ferroelectric properties. Generically, all such materials utilize either the electric or magnetic eld producing means in conjunction with such devices and have properties beneficial to the device operating parameters. In different applications such materials are disposed in different areas within the device. Any configurations including slabs, discs, as Well as rods, can be utilized with the disclosed structure. The exotic materials are shielded from the thermal effects of the tube manufacturing operations and may be readily replaced without destroying the evacuated atmosphere of the device.

A dielectric material may be utilized in the formation of the encapsulation structure and be bonded to the metallic walls defining the tube envelope by conventional dielectric sealing processes. The mechanical positioning of the exotic materials eliminates essentially all of the prior art limitations in the utilization of such materials. Additionally, means for the circulation of coolant fluids in proximity to the exotic materials are incorporated in the design of the encapsulation structure. The provision of such coolant circulation capability extends the operating temperature range of such electron interaction devices incorporating the exotic materials. All of the aforementioned types of devices in either linear or circular configuration may be utilized in the illustrative embodiments of the inveniton. The encapsulating structures are desirably disposed adjacent to certain electrodes such as for example the slow wave propagating structure where the magnetic or electric properties of these materials may be utilized in conjunction with the conventional tube interaction phenomenon. Devices having mutually perpendicular electric and magnetic fields as well as parallel fields are included in the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, as well as an illustrative embodiment, will now be described, reference being directed to the accompanying drawings in which:

FIG. l is a longitudinal cross-sectional view of an exemplary crossed field embodiment of the invention;

FIG. 2 is a vertical cross-sectional view along the lines 2 2 in FIG. 1 viewed in the direction of the arrows; and

FIG. 3 is a vertical cross-sectional view of an alternative embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, FIG. 1 illustrates a linear crossed field device having an interdigital slow wave conducting structure having individual elements 11 Ifor the propagation of electromagnetic wave energy which interacts with an adjacent electron beam. Spaced from and parallel with the slow Wave structure is a sole electrode 12 to define an electron interaction path 13 therebetween. In accordance with prior art teachings the slow wave structure may be negatively or positively biased with the opposing sole electrode at the opposite potential. The resultant electric field between the electrodes is indicated by the arrow 14 and E. A cathode gun assembly 15 in cooperation with an opposing biased accelerator electrode 16 provides the desired beam trajectory for the electrons along the path 13. At the opposing end of the electron interaction path is a collector electrode 17 connected to suitable external circuitry. The foregoing components are housed Within a metallic envelope 18 having end walls 19. The envelope is evacuated in the area indicated by the numeral 20 by conventional processing techniques.

Magnetic field producing means comprising either a permanent magnet or electromagnet designated generally by the numeral 23, shown in FIG. 2, provides a magnetic field mutually perpendicular to the electric field. A circle and cross 22 indicates the disposition of the magnetic field within the device.

Referring again to FIG. 1, as well as FIG. 2, the embodiment of the invention 24 is shown as abutting the top wall 21 of the envelope 18 and extends in close proximity to the slow wave structure 10. The boxlike encapsulated structure comprises a plurality of parallel sidewall members 25 of a microwave permeable material. The dimensions of the sidewall members as well as other components of the boxlike encapsulating structure are selected in accordance with the desired characteristics attainable with the exotic material maintained therein. A bottom wall 26 joined between the sidewalls is composed of a similar material and if desired the entire structure may be fabricated of a single U-shaped configuration. The thickness of the members 25 and 26 is selected to minimize the dielectric loading effects and yet provide suflicient mechanical strength to support the housed material. The sidewalls are brazed to the metal top wall 21 throughout the length by conventional brazing techniques to provide a vacuum seal to thereby isolate the contained material from the evacuated portion 20 of the tube envelope. Suggested materials for the encapsulating structure include alumina or beryllia or a mixture of magnesium oxide and aluminum oxide. The primary criterion resides in the low dielectric loss and electromagnetic wave permeability. End walls 27 of a similar material complete the encapsulating structure.

The housed material, illustratively a ferrite body 3f), is retained within the encapsulated structure by means of retention member 28 of an inverted U-shaped configuration defining a channel 29. The retention member 28 may be of a similar composition as the encapsulating member walls. Since this member is not exposed to the vacuum atmosphere a critical seal is not required. Member 28 may, therefore, be simply mechanically positioned within the encapsulating structure or may be -brazed to the adjacent metallic surface. Access to the interior of the encapsulating structure may be had by providing suitable openings in the top wall 21 in any desired manner to thereby enhance ready removal and replacement of the ferrite material. The dimensions of the exotic material including its length, thickness and width will be determined by the desired characteristics for influencing the output of the applicable embodiment.

The channel 29 provides means for the flow of a coolant fluid through the encapsulating structure to thereby provide `for higher operating temperatures of the materials within the encapsulating structure. An inlet port 31 extending within the top wall 21 is provided as well as outlet port and connector '32 also extending through the top wall 21. Any liquid coolant circulated from an external source of conventional structure and therefore not illustrated is circulated through the channel 29 to thereby directly engage the ferrite body 30. The cooling action is direct and oil or any other coolant liquids having a low dielectric loss characteristic may be employed.

In the foregoing embodiment the ferrite body 30 has been illustrated as being mechanically retained in its desired posititon in view of the noncritical nonvacuum area within the encapsulated structure. In certain specific applications it may be desirable due to excessive vibration to provide a bond along the contacting surface 41 of retention member 28 abutting the ferrite material 30. This bond would not be required to have the thermal or vacnum properties of the remaining bonds in the embodiment. A simple glass bond, therefore, could be provided between the surface 41 and the ferrite body 30 to thereby damp any environmental vibrations.

In the foregoing description the disposition of a ferrite material within a microwave oscillator and/or amplifier has been discussed. The invention also encompasses the incorporation of other heretofore distributed components such as for example phase shifting means within a microwave oscillator or amplifier. In FIG. 3 such a combination is disclosed wherein phase shifting means 36 is housed within a compartment '35 within retention member 33. In this embodiment structural components of similar composition and configuration to those shown in FIGS. l and 2 have been similarly numbered. Cooling of the enclosed phase shifting means is provided by means of spacing the member 33 an appropriate distance from top Wall 21 to define a channel 34. The coolant liquid may then be circulated through the appropriate connectors within the channel and, therefore, remove the heat generated from the adjacent components. In this embodiment retention member 33 will be suitably sealed to bottom member 26 disposed between the sidewalls 2S to prevent any impedance of the coolant ow by movement of this retention member in the channel 34. The phase shifter included a cylindrical ferrite element 37 supported by dielectric means 38 of well known composition. Surrounding the ferrite element is a solenoid electromagnet 39 which is connected by means of leads 40 extending through top wall 21 to a suitable voltage biasing source. In this manner a phase shifting device is incorporated Within a device, illustratively an oscillator or amplifier, which reduces by a large factor the cost and load effects of associated distributed components.

Other combinations will readily be apparent to those skilled in the art. The circular type of microwave devices are also readily adapted to the present invention. The existing magnetic and electric field producing means are readily available for use with the exotic materials incorporated within the tube envelopes. In phase shifting applications, however, where a different value of phase shift may be required for different directions of propagation a separate electromagnet biasing means is incorporated with the phase shifter as discussed in relation to FIG. 3.

An excellent structure is herein provided for the incorporation of the so-called exotic materials within evacuated electron interaction devices. It will also be readily apparent that with the encapsulated structure of dielectric materials tube brazing operations at high temperatures will not in any way be harmful to the housed materials. Many variations, modifications and alterations will be apparent to those skilled in the art. lt is intended, therefore, that this description of an illustrative embodiment be considered as exemplary only without limiting in any way the interpretation of the scope of the invention in its broadest aspects as set forth and defined in the appended claims.

What is claimed is: 1. ln combination: an electron interaction device defining a metallic envelope enclosing a plurality of electrodes in an evacuated atmosphere; means for producing electric and magnetic fields in said envelope; and means defining an enclosure within said envehope and outside said evacuated atmosphere for housing materials properties and selected from the group consisting of ferrites, ferrimagnetic materials,

ferromagnetic materials, semiconductor materials and -ferroelectric materials, said materials being beneficial to the operation of the device in conjunction with said electric and magnetic fields and removed from the influence of the evacuated atmosphere. 2. The combination according to claimrl wherein said materials exhibit ferromagnetic properties.

'3. The combination according to laiin 1 wherein said materials exhibit ferroelectric properties.

4. The combination according to claim materials exhibit ferrimagnetic properties.

. An electron interaction device comprising: a metallic evacuated envelope; a plurality of electrodes disposed within said envelope; means for producing electric and magnetic fields between said electrodes; and means for incorporating within said envelope materials having electromagnetic properties and selected from the group consisting of ferrites, ferrimagnetic materials, ferromagnetic materials, semiconductor materials and ferroelectric materials, said materials being in close proximity to said electrodes to inuence the operation of said device; said means comprising an encapsulating structure supenvelope and defining a nonevacuated atmosphere within which said material is supported. 6. An electron interactiton device according to claim 5 wherein said encapsulating structure encloses an electromagnetic energy phase shifting means.

7. An electron interaction device comprising: an evacuated envelope; a plurality of electrodes disposed within said envelope; means for producing electric and magnetic fields between said electrodes; means for incorporating within said envelope materials having electromagnetic properties beneficial to the operation of the device in co junction with said electric and magnetic fields; said means comprising an encapsulating structure supported by said envelope and defining a nonevacuated atmosphere within which said material is mechanically supported;

and means for circulating a coolant fluid within said encapsulating structure.

8. An electron interaction device comprising:

an evacuated envelope;

a plurality of electrodes disposed within said envelope;

with- 1 wherein said means for producing electric and magnetic fields tween said electrodes;

and means for incorporating within said envelope a electromagnetic properties beneficial to the operation of the device in conbody of a material having junction with said electric and magnetic fields;

said means comprising wa and thermally bonded to the interior of said envelope to define a nonevacuated enclosure; a retaining member contact with said body;

said retaining member having wall structure defining a passageway in close proximity to said body;

and means for circulating a coolant fluid within said passageway.

9. An electron interaction device according to claim enclosure wall members are of a low loss energy permeable dielectric ma- 8 wherein said electromagnetic wave terial.

10. An electron interaction device an evacuated envelope; a slow trode defining therebetween path within said envelope;

comprising:

along said path;

means for producing electric and magnetic fields within said envelope;

proximity to said interaction in conjunction with said electric and magnetic fields; said means comprising a bonded to said envelope atmosphere within and defining enclosure. 11. A crossed field microwave device comprising:

an evacuated envelope;

a slow wave propagating structure and opposing elecan electron interaction trode defining therebetween path within said envelope;

means for generating and directing an electron beam along said path; means for producing and magnetic fields within said envelope; and means for incorporating within said close proximity to said operation of the device in onjunction with crossed electric and magnetic fields; said means comprising wall members boxlike enclosure having a within which said material is supported.

12. A device according to ble dielectric material.

References Cited UNITED STATES PATENTS 2,798,203 7/ 1957 Robertson 315--3 2,941,115 6/ 1960 Meixner S15- 5.1 2,964,669 12/ 1960 Enander 315--3 3,144,616 8/1964 Iepsen 315--35 3,333,148 7/1967 Buck S15-39. 3,334,267 7/ 1967 Plumridge 3l5-39.

HERMAN KARL SAALBACH, Primary Examiner SAXFIELD CHATMON, In., Assistant Examiner U.S. Cl. XR.

ll members joined together disposed within said enclosure in wave propagating structure and opposing elecan electron interaction means for generating and directing an electron beam boxlike enclosure thermally a nonevacuated which said material is positioned; and means for circulating a coolant fluid within said mutually perpendicular electric envelope in interaction path materials having electromagnetic properties beneficial to the said joined together and thermally bonded to said envelope to define a nonevacuated atmosphere claim 11 wherein said wal members are composed of a low loss microwave permea 

